from qrcode import constants

EXP_TABLE = list(range(256))

LOG_TABLE = list(range(256))

for i in range(8):
    EXP_TABLE[i] = 1 << i

for i in range(8, 256):
    EXP_TABLE[i] = (
        EXP_TABLE[i - 4] ^ EXP_TABLE[i - 5] ^ EXP_TABLE[i - 6] ^
        EXP_TABLE[i - 8])

for i in range(255):
    LOG_TABLE[EXP_TABLE[i]] = i

RS_BLOCK_OFFSET = {
    constants.ERROR_CORRECT_L: 0,
    constants.ERROR_CORRECT_M: 1,
    constants.ERROR_CORRECT_Q: 2,
    constants.ERROR_CORRECT_H: 3,
}

RS_BLOCK_TABLE = [

    # L
    # M
    # Q
    # H

    # 1
    [1, 26, 19],
    [1, 26, 16],
    [1, 26, 13],
    [1, 26, 9],

    # 2
    [1, 44, 34],
    [1, 44, 28],
    [1, 44, 22],
    [1, 44, 16],

    # 3
    [1, 70, 55],
    [1, 70, 44],
    [2, 35, 17],
    [2, 35, 13],

    # 4
    [1, 100, 80],
    [2, 50, 32],
    [2, 50, 24],
    [4, 25, 9],

    # 5
    [1, 134, 108],
    [2, 67, 43],
    [2, 33, 15, 2, 34, 16],
    [2, 33, 11, 2, 34, 12],

    # 6
    [2, 86, 68],
    [4, 43, 27],
    [4, 43, 19],
    [4, 43, 15],

    # 7
    [2, 98, 78],
    [4, 49, 31],
    [2, 32, 14, 4, 33, 15],
    [4, 39, 13, 1, 40, 14],

    # 8
    [2, 121, 97],
    [2, 60, 38, 2, 61, 39],
    [4, 40, 18, 2, 41, 19],
    [4, 40, 14, 2, 41, 15],

    # 9
    [2, 146, 116],
    [3, 58, 36, 2, 59, 37],
    [4, 36, 16, 4, 37, 17],
    [4, 36, 12, 4, 37, 13],

    # 10
    [2, 86, 68, 2, 87, 69],
    [4, 69, 43, 1, 70, 44],
    [6, 43, 19, 2, 44, 20],
    [6, 43, 15, 2, 44, 16],

    # 11
    [4, 101, 81],
    [1, 80, 50, 4, 81, 51],
    [4, 50, 22, 4, 51, 23],
    [3, 36, 12, 8, 37, 13],

    # 12
    [2, 116, 92, 2, 117, 93],
    [6, 58, 36, 2, 59, 37],
    [4, 46, 20, 6, 47, 21],
    [7, 42, 14, 4, 43, 15],

    # 13
    [4, 133, 107],
    [8, 59, 37, 1, 60, 38],
    [8, 44, 20, 4, 45, 21],
    [12, 33, 11, 4, 34, 12],

    # 14
    [3, 145, 115, 1, 146, 116],
    [4, 64, 40, 5, 65, 41],
    [11, 36, 16, 5, 37, 17],
    [11, 36, 12, 5, 37, 13],

    # 15
    [5, 109, 87, 1, 110, 88],
    [5, 65, 41, 5, 66, 42],
    [5, 54, 24, 7, 55, 25],
    [11, 36, 12],

    # 16
    [5, 122, 98, 1, 123, 99],
    [7, 73, 45, 3, 74, 46],
    [15, 43, 19, 2, 44, 20],
    [3, 45, 15, 13, 46, 16],

    # 17
    [1, 135, 107, 5, 136, 108],
    [10, 74, 46, 1, 75, 47],
    [1, 50, 22, 15, 51, 23],
    [2, 42, 14, 17, 43, 15],

    # 18
    [5, 150, 120, 1, 151, 121],
    [9, 69, 43, 4, 70, 44],
    [17, 50, 22, 1, 51, 23],
    [2, 42, 14, 19, 43, 15],

    # 19
    [3, 141, 113, 4, 142, 114],
    [3, 70, 44, 11, 71, 45],
    [17, 47, 21, 4, 48, 22],
    [9, 39, 13, 16, 40, 14],

    # 20
    [3, 135, 107, 5, 136, 108],
    [3, 67, 41, 13, 68, 42],
    [15, 54, 24, 5, 55, 25],
    [15, 43, 15, 10, 44, 16],

    # 21
    [4, 144, 116, 4, 145, 117],
    [17, 68, 42],
    [17, 50, 22, 6, 51, 23],
    [19, 46, 16, 6, 47, 17],

    # 22
    [2, 139, 111, 7, 140, 112],
    [17, 74, 46],
    [7, 54, 24, 16, 55, 25],
    [34, 37, 13],

    # 23
    [4, 151, 121, 5, 152, 122],
    [4, 75, 47, 14, 76, 48],
    [11, 54, 24, 14, 55, 25],
    [16, 45, 15, 14, 46, 16],

    # 24
    [6, 147, 117, 4, 148, 118],
    [6, 73, 45, 14, 74, 46],
    [11, 54, 24, 16, 55, 25],
    [30, 46, 16, 2, 47, 17],

    # 25
    [8, 132, 106, 4, 133, 107],
    [8, 75, 47, 13, 76, 48],
    [7, 54, 24, 22, 55, 25],
    [22, 45, 15, 13, 46, 16],

    # 26
    [10, 142, 114, 2, 143, 115],
    [19, 74, 46, 4, 75, 47],
    [28, 50, 22, 6, 51, 23],
    [33, 46, 16, 4, 47, 17],

    # 27
    [8, 152, 122, 4, 153, 123],
    [22, 73, 45, 3, 74, 46],
    [8, 53, 23, 26, 54, 24],
    [12, 45, 15, 28, 46, 16],

    # 28
    [3, 147, 117, 10, 148, 118],
    [3, 73, 45, 23, 74, 46],
    [4, 54, 24, 31, 55, 25],
    [11, 45, 15, 31, 46, 16],

    # 29
    [7, 146, 116, 7, 147, 117],
    [21, 73, 45, 7, 74, 46],
    [1, 53, 23, 37, 54, 24],
    [19, 45, 15, 26, 46, 16],

    # 30
    [5, 145, 115, 10, 146, 116],
    [19, 75, 47, 10, 76, 48],
    [15, 54, 24, 25, 55, 25],
    [23, 45, 15, 25, 46, 16],

    # 31
    [13, 145, 115, 3, 146, 116],
    [2, 74, 46, 29, 75, 47],
    [42, 54, 24, 1, 55, 25],
    [23, 45, 15, 28, 46, 16],

    # 32
    [17, 145, 115],
    [10, 74, 46, 23, 75, 47],
    [10, 54, 24, 35, 55, 25],
    [19, 45, 15, 35, 46, 16],

    # 33
    [17, 145, 115, 1, 146, 116],
    [14, 74, 46, 21, 75, 47],
    [29, 54, 24, 19, 55, 25],
    [11, 45, 15, 46, 46, 16],

    # 34
    [13, 145, 115, 6, 146, 116],
    [14, 74, 46, 23, 75, 47],
    [44, 54, 24, 7, 55, 25],
    [59, 46, 16, 1, 47, 17],

    # 35
    [12, 151, 121, 7, 152, 122],
    [12, 75, 47, 26, 76, 48],
    [39, 54, 24, 14, 55, 25],
    [22, 45, 15, 41, 46, 16],

    # 36
    [6, 151, 121, 14, 152, 122],
    [6, 75, 47, 34, 76, 48],
    [46, 54, 24, 10, 55, 25],
    [2, 45, 15, 64, 46, 16],

    # 37
    [17, 152, 122, 4, 153, 123],
    [29, 74, 46, 14, 75, 47],
    [49, 54, 24, 10, 55, 25],
    [24, 45, 15, 46, 46, 16],

    # 38
    [4, 152, 122, 18, 153, 123],
    [13, 74, 46, 32, 75, 47],
    [48, 54, 24, 14, 55, 25],
    [42, 45, 15, 32, 46, 16],

    # 39
    [20, 147, 117, 4, 148, 118],
    [40, 75, 47, 7, 76, 48],
    [43, 54, 24, 22, 55, 25],
    [10, 45, 15, 67, 46, 16],

    # 40
    [19, 148, 118, 6, 149, 119],
    [18, 75, 47, 31, 76, 48],
    [34, 54, 24, 34, 55, 25],
    [20, 45, 15, 61, 46, 16]

]


def glog(n):
    if n < 1:  # pragma: no cover
        raise ValueError("glog(%s)" % n)
    return LOG_TABLE[n]


def gexp(n):
    return EXP_TABLE[n % 255]


class Polynomial:

    def __init__(self, num, shift):
        if not num:  # pragma: no cover
            raise Exception("%s/%s" % (len(num), shift))

        offset = 0

        for item in num:
            if item != 0:
                break
            offset += 1

        self.num = [0] * (len(num) - offset + shift)
        for i in range(len(num) - offset):
            self.num[i] = num[i + offset]

    def __getitem__(self, index):
        return self.num[index]

    def __iter__(self):
        return iter(self.num)

    def __len__(self):
        return len(self.num)

    def __mul__(self, other):
        num = [0] * (len(self) + len(other) - 1)

        for i, item in enumerate(self):
            for j, other_item in enumerate(other):
                num[i + j] ^= gexp(glog(item) + glog(other_item))

        return Polynomial(num, 0)

    def __mod__(self, other):
        difference = len(self) - len(other)
        if difference < 0:
            return self

        ratio = glog(self[0]) - glog(other[0])

        num = self[:]

        num = [
            item ^ gexp(glog(other_item) + ratio)
            for item, other_item in zip(self, other)]
        if difference:
            num.extend(self[-difference:])

        # recursive call
        return Polynomial(num, 0) % other


class RSBlock:

    def __init__(self, total_count, data_count):
        self.total_count = total_count
        self.data_count = data_count


def rs_blocks(version, error_correction):
    if error_correction not in RS_BLOCK_OFFSET:  # pragma: no cover
        raise Exception(
            "bad rs block @ version: %s / error_correction: %s" %
            (version, error_correction))
    offset = RS_BLOCK_OFFSET[error_correction]
    rs_block = RS_BLOCK_TABLE[(version - 1) * 4 + offset]

    blocks = []

    for i in range(0, len(rs_block), 3):
        count, total_count, data_count = rs_block[i:i + 3]
        for j in range(count):
            blocks.append(RSBlock(total_count, data_count))

    return blocks
